Stereo speaker



FIG. 1 is a front and right side perspective view of a stereo speaker, showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof, the left side being a mirror image; and

FIG. 4 is a rear elevational view thereof. 

The ornamental design for a stereo speaker, as shown and described. 